A day after the strategic Afghanistan city of Kanduz fell to the Taliban, the insurgents have tightened their hold despite US airstrikes.

They fanned out in full force, closing roads, throwing up checkpoints and torching government buildings as fearful residents huddled indoors.

US warplanes carried out two airstrikes on Taliban positions, but Afghan government ground troops sent to try to retake Kunduz, one of Afghanistan's wealthiest cities, were stalled by roadblocks and ambushes, unable to move closer than about a mile towards their target.

A Nato officer said more airstrikes were unlikely as "all the Taliban are inside the city and so are all the people".

His words suggested the fight to retake the city would involve painstaking street-by-street fighting as government forces try to avoid civilian casualties in retaking control.

Inside the city, residents were stunned by the audacity of the insurgents, who attacked Kunduz on a number of fronts before dawn on Monday, taking the government, intelligence agency and military by surprise.

The insurgents used mosque loudspeakers to try to reassure people they were safe. But residents, recalling the group's brutality during its 1996-2001 rule of Afghanistan, were fearful of what was to come.